Field of the Invention
The invention relates to a pumped storage power plant for energy storage for energy generated from renewable sources, and to methods for energy storage using a pumped storage power plant.
Background Description
The invention relates in general to the field of energy storage for energy generated from renewable sources such as, for example, wind power or solar power. Since these types of energy generation are subject to irregularities, depending on weather, the need to store energy is becoming ever more important. Besides electrochemical storage, which is relatively demanding of resources, there are already proposals to implement a storage as mechanical energy, e.g. in so-called pumped storage hydropower plants or compressed air energy storage plants. Hitherto, pumped storage hydropower plants have been constrained locally by the geological conditions above ground, and new projects have encountered social acceptance problems because of their visual impact in the natural environment. Compressed air energy storage plants are socially acceptable, owing to the fact that it is possible for the chambers to be installed underground, but hitherto they have had relatively low efficiencies, and therefore a low energy efficiency. Pumped storage hydropower plants have therefore hitherto been realized only in landscapes with appropriate height differences. In landscapes such as the North German lowland, or on the open sea, where a large part of the wind energy is generated, the use of conventional pumped storage hydropower plants proves to be unrealistic.
There are already proposals, such as, for example, in EP 0 212 692 B1, to implement an energy storage in two underground storage spaces disposed at different depths. However, implementation of such proposals is thwarted by the problems of installing and operating appropriate pumping machines at great depth below the ground surface, in order to pump the liquid used from a lower storage space into the upper storage space. It is technically not feasible for liquid to be extracted by suction from a relatively deep lower storage space (e.g. at a depth of several 100 or 1000 m) by a pumping machine disposed above ground.